As graziers, we all focus on good manure distribution as a way of keeping nutrients in our soils so we have better forage for our animals. We thought that knowing what the nutrient composition of animal manures might help us better understand what we’re accomplishing with our good manure management practices.

While substitutes can be found for many finite natural resources mined from the Earth—copper in phone lines can be replaced by fiber optics, steel in car bodies by composite plastics, and petroleum in transportation fuels by biodiesel or hydrogen cells—this is not the case for phosphorus in food production. The U.S. Geological Survey lists the following under the heading Substitutes for Phosphate Rock: “THERE ARE NO SUBSTITUTES FOR PHOSPHORUS . . . ”